FROM THE TREATMENT OF FATTY MATTERS
The most important industrial products obtained from the treatment
of fatty matters are : boiled linseed oil, oxidised oils, hardened or hydro-
genised oils, Turkey-red oils, oleine, stearine, candles, soap and glycerine.
The methods of analysis used for these materials are largely those em-
ployed with fatty substances, being based mainly on the determinations
of the various characters (specific gravity, melting point, acid number,
saponification number, iodine number, etc.), for which the general methods
of the preceding chapter are used. Any special tests necessary are described,
as occasion offers, in the following articles.
BOILED LINSEED OIL
Boiled linseed oil is fluid but more viscous than the crude oil, and is
more or less brownish-yellow or brown and of a peculiar odour; there is
also a very thick, almost pasty form, which is brown with a greenish fluores-
cence and has a very marked odour-,
In general, the boiled oil is distinguished from the ordinary or crude
form by the appearance, the smell, the high specific gravity (0-937-0-99),
the presence of drying agents (these are sometimes absent, in which case
the distinction is readily made by other characters) and especially by the
ease with which it dries.
Boiled linseed oil may be found mixed or adulterated with resin, resin
oil, mineral oil, fish or blubber oil, or vegetable oil (colza, soja bean, etc.).
Its analysis includes the following determinations and tests:
1. Specific Gravity, Iodine Number, Saponification Number,
Acid Number .—By the general methods given in the preceding chapter.
2. Detection of Extraneous Oils.—As in ordinary linseed oil (see p.
3. Detection of Unsaponifiable Substances and Volatile Oils.—
A few grams of the oil are saponified with alcoholic potash in the usual
way and then diluted with 2-3 vols. of water : if the oil is pure the solution
is clear or contains a few flocks of lead or manganese hydroxide if dryers are
present, but a turbid liquid is obtained if the oil contains mineral or resin oils.